Marbling plastic sheet



April 10, 1956 R. c. Hess ErAL 2,740,991

MARBLING PLASTIC SHEET Filed May 3, 1952 *Second Calender Blle Colored Slvers Baffle Plfe Hol Granules Folding Molllmg /z/ Foldlng Mollllng Bank Bank Mollled Surface Compound Granules Frsr Calender Ble y" @A l/Mo/IvgvE '2253925 5||VVS 0f C|red Lou/s L cA/PENTER I ComPOund Z WALDEMAR HoRsTEME/ER @l I BY ATTORNEY United Ses.,rPaer1f MARBLING rLAsrlc snnsr Raymond C. Hess, Westfield, and Louis L. Carpenter and Waldemar Horstemeier, Plainfield, N. J., assignors .to Union Carbide and Carbon Corporation, a corporation of New York 'Application May' s, 1952,'sena1 No. 5,924 6 claims. (ci. 1s4s.'s)

This invention relates to marbling plastic sheet, and more particularly to a calender processy for embodying color material into the base sheeting to produce a motcolored mottling compounds on the offset roll side, or

eventual wearing surface side of the calendered sheet. It has been found that a more sharply defined mottle can be produced when the color is added to the top rather than to the back of the sheet. v

The mottling bank at the second bite is the most important single factor in obtaining a good marbled sheet.

t 'l` his bani: is of a folding rather than a rolling type. The

ded-effect simulating the characteristic appearance of i variegated marble.

While the invention is of general application to plastic sheeting of all kinds, it is particularly directed to hard surface iioor coverings, and especially to continuous roll material with a felt backing and simulating inlaid linoleum. For this purpose, the vinyl resins have advantages of excellent abrasion and chemical resistance, the ability to produce better whites and pastel shades, and the low inventory of raw materials in process.

In an endeavor to produce a variegated color effect, when chips of color material are fed to base material and then calendered, the color material is elongated, streaked or-smeared, and produces a unidirectional pattern somewhat similar to the grain of wood, and known as a jaspe pattern, as distinguished from' the desired mottled multidirectional or non-directional pattern characteristic of variegated marble. This effect is largely due to the cus-Y tomary rolling bank at the second bite of the calender rolls. A rolling bank will break upthe color to some extent, but in the calender direction only. Thus arolling bank results in long streaks of .color extending in the*r calender direction.

The linoleum industry has coped with this problem and produced a marbled effect by calendering a; sheet, cutting` the sheet into sections, turning the sections through a right,`

angle, and calendering a second time in a direction transverse to the rst calendering. This process is costly and laborious, and it is therefore the main object of the present invention to provide a continuous vsingle calender process to produce a marbled plastic sheet having a sharp, well defined mottle or variegation. i H

According to the present invention, marbled plastic sheet is produced by feeding base plasticand pieces' of color plastic to the yfirst bite of a calenderin'gV operation, and passing the plastics from said first bite to a folding mottling bank at a second bite in the-calendering operation. Preferably the base plastic is in the form of hot granules, and the color plasticis inthe form of slivers. A baffle plate is mounted between the top roll and the offset roll of the calender. The base compound granules are fed between the batiie and the top roll, and the color slivers are fed simultaneously between the other side of the baie and the oiset roll, the slivers being fed in aligned relation disposed transversely to the direction of calendering.

ln the lirst bite, the base granules are commingled with eachother and compressed and cohered to form a sheet of plastic, and the color slivers are simultaneously embedded in the face side of `said base sheet and compressed to disrupt their edges to intermingle with the base plastic thereunder'and therebetween. n

The purpose of the baie `is two-fold: (a) it maintains a `constant feed and uniform ilow of base compound granules to the first calender bite, and (b) it places the type of bank obtained at this point is dependent upon the temperature, the temperature differential between the top` and middle rolls, the feed to the lirst bite, and the compound formulation.

In the drawings:

Fig. 1 is a diagramk of a four-roll inverted L-type calender adapted for carrying out the process according to the present invention;

Fig. 2 is a front view of the sheet passing from the iirst calender bite;

Fig. 3 is a front View of the sheet passing through the folding mottling bank at the second calender bite;

Fig. 4 is a cross `section through the folding mottling bank, taken along the line 4 4 of Fig. 3; and

Fig. 5 is a top view of the finished product.

According to the preferred embodiment of the present invention, the base compound which forms the backgroun-d of the pattern is uxed in a Banbury mixer to a temperature of 140 C. This base compound is then given two passes on the two roll mill with surface temperatures of 1Z0-125 C., then fed to a granulato-r while still hot. The hot granules at ll0 C. are then fed to the first bite of a four roll L-type calender and calendered to a 0.027 sheet, using temperatures of 105 C. offset roll, 122 C. top roll, and 110 C. middle roll. The bottom roll is used as a take-ofi roll.

A hot granular stock proved to be the best form for feeding the base compound to the calender. Flow behavior allows the base stock to be placed into the bite in a position which allows the colored mottling stocks to be also fed uniformly into the bite, and granular stock provides a more uniform compound temperature than any other form of feed. A constant rate of feed to the firstv bite is essential to maintain a good mottling at the second bite.

As shown in Fig. l, the` base compound granules are introduced between the top roll and the baffle plate at the first bite, and colored compounds-in the form of slivers are fed between the offset roll and the baie plate, so as to be simultaneously introduced into the same first bite between the top roll and the offset roll.

The colored compounds are fed cold, because heating thereof would result in 4the color being drawn out too far in the calender direction on passing through the first bite. The only Working required in this iirst pass is that the co1- ored stocks be embedded inthe base compound and be drawn out as little as possible. Slivers of the mottling compounds one sixteenth to one quarter inch wide, onehalf to three inches long, and twenty thousandths of an inch thick provided the best resultsv and gave the most desirable marbleization.

The slivers are fed with their lengths transverse to the calender'direction. This produces a two-directional color break-up. Care must be exercised to avoid feeding the By varying these there is a wide choiceof patimportant adjustment in 'its installation. The proper depthisthatat whichthere is no owof base-compound granules to the area between the offset roll and the baffie. If such fiow occurs, it interferes with the flow of the mottling compounds into the bite land resultsin'poor color distributioniinlthesheet.

'The -sheet of yplastic with color compound Vembedded therein, as formed in the flirst 'bitebetween the top roll and the odset roll, passes along the toproll andlapproaches the middle roll, where it enters the foldingmottlingbank at -the bite between :the top roll and the middle ro'll, as shown in Fig. 4.

In this Ifolding and -mottling bank, 'the voncoming sheet encounters Ythe -excess lof preceding Amaterial accumulated attthe'b'itezbetween the top roll'andthe ymiddle roll. lBeing of relatively stiff consistency and havingilittle adhesion to the middle roll, it leaves the middle rollintermittently to double over, and returns to the said second bite in multiple thicknesses lof superimposed folds. -These superimposed fol-ds interrupt or prevent the longitudinal extensienof-the color, and increase the number of lthicknesses entering the second bank and thereby increase'the lateral spread'of the color.

This mottling Ibank at the second calender bite must therefore be a folding rather than a rolling bank to obtain marbling. VIt is vthis folding action which makes possible the marble ercct. The size of the mottling bank is one of the factors determining the type of color marbling obtained. Ilt must be large enough to form breaking folds but must at the same time be maintained small enough to avoid fingering. The formation of cold fingers as a result of too large a bank may produce streaks in the calendered sheet. After the optimum size of bank is established, it must be maintained at approximately that size to insure satisfactory marbling and uniformity of pattern.

Under the above conditions a very good marbleized sheet can be calendered at ten feet per minute on an '18 inch by 48 linch calender. Pig. 5 illustrates such a sheet.

Upon increasing the speed to l5 ft. per minute without changing roll temperatures the folding mottling bank becomes a rolling bank and Apoor mar-bling results. The rolling bank indicates a higher compound temperature which is the result of the `increased calendering speed. Thus the problem of maintaining the desired folding mottling bank at calendering speeds above ten feet per minute is one of temperature control.

Uniformity of bank size across its entire width is likewise important. The offset roll must be properly contoured 'to give such a uniform bank, otherwise different types of color `mottlingwill result across the width of the sheet.

It must be understood that the conditions outlined for producing a good marbled sheet were established for the particular equpipment used. Some of these conditions will undoubtedly be modified in converting to larger production scale installation. Size of mottling bank for example, will depend largely on the size of calender rolls. Processing temperatures at the various stages will also most likely be modified. For example, granulation of the base compound might be most conveniently effected by `a scratcher :operation which would necessitate the use of higher Banbury temperatures and mill temperatures to insure good adhesion of the base compound sheet to the mill. ln short, optimum processing conditions will have to be established for the particular operation.

We claim:

l. vlvet'ncd of producing plastic sheet having a marbled appearance which comprises continuously and simultaneously feeding a base of plastic material and pieces of colored plastic material to the first bite of a calendering operation, forming at said first bite a longitudinally continuous intermediate sheet ofcolore'd plastic material wherein the pieces of colored plastic material are embedded .in the base material, passing said intermediate sheet continuously in..

its longitudinal direction at calendering speeds to a sec- -ondbiteinthe-'calendering'operationaand controllingthe temperature at said second bite with respect to the calender speed to produce a folding mottling bank at said second bite wherein distribution of the colored pieces embedded in the base material occurs to produce a marbled effect.

2. Methodofjproducingplastic sheet having a marbled appearance, which comprises continuously feeding hot grantiles'of baseplas'ticnrraterial tolthefirstbite 'of acalendering operation, sitrttiltaneouslyA continuously feedingcold slivers of clored plastic material to the samefirstbiten substantially aligned relation transverse to the direction of calendering and in spaced relation 'longitudinalthereto, forming at said :firstfbite 1a longitudinally continuous intermediate sheet of colored plastic material wherein the slivers of colored plastic material are embedded in the base material, passing said intermediate sheetcontinuously in its longitudinal-direction at calendering speeds to a second bite in the calendering Voperatiomand controlling the temperature at said second bite with respect `to the calender speed to produce a folding mottling bank at said ysecond bite wherein the colored slivers embedded in the base material are distributedto produce a marbled effect.

3. -Method of producing plastic sheet having a marbled appearance, which .comprises continuously feeding 4granules ofbase plasticmaterial to the top roll side of the first bite of a tcalendering operation, simultaneously continuouslyfeeding pieces ofcolored plastic material to the 'olfset roll side of the first bite, continuously forming atrsaid first 'bite a longtudinally continuous intermediate sheet of colored-plastic material wherein the pieces of colored plastic material are :embedded in the base plasticand 'formed into an intermediate sheet, passing said intermediate'sheet continuously 'in .its longitudinal direction at calendering speed to afsecondlbite in the calendering loperation, and controllingthe temperature at said second bite with respect to the '.calendering speed to produce a folding mottling bank `at-said second bite wherein the colored pieces ernbedded in the base material are distributed to produce a marbled effect. l

4. Method yof Aproducing plastic sheet having a marbled appearance, which comprises continuously 'feeding a base of plastic `Vmaterial'to tne first bite of a calender'ingI operation, simultaneously continuously feeding pieces of color plastic material to the same first bite whereby the colored plastic material is embedded in the base plastic material-,and formed into a longitudinally continuous intermediate sheet, passing said intermediate .sheet :from 'said first Yb'ite continuously at calendering speed in its longitudinal direction to a second-bite parallel to said .first bite of the calendering operation, and controlling the temperature at said second lbite with respect to the calendering speed .toform afbankwherein theoncoming sheet from the first bite encounters the bank, doublesfover and returns to the second .bite 4in multiple thicknesses of superimposed folds.

5. Method of producing plastic sheet having a marbled appearance, in acalender having a baflie between the top roll and the offset roll, which comprises continuously 'feeding hot granules of base plastic material between 'the top roll and the baille, simultaneously continuously feeding cold slivers of colored plastic material between the offset roll and the battle in substantially aligned relation transverse to the direction of calendering whereby the colored plastic'materi'al is embedded in the base plastic material and formed into a longitudinally continuous intermediate sheet, passing said intermediate sheet on the top roll continuouslyin .its longitudinal direction at calendering speedl to a parallel roll therebelow, and controlling the .temperature on said top roll with respect to the calendering speed to form a bank wherein the oncoming sheet on 4the top' roll encounters the bank at the bite between the top roll and the roll therebelow, doubles over and returns to said bite in multiple thicknesses of superimposed folds.

6. Method of producing pli stic sheet having a marbled appearance, which comprises continuously feeding a base of plastic material to the first bite of a calendering operation, simultaneously continuously feeding pieces of colored plastic material to the same first bite of said calendering operation wherein an intermediate sheet of plastic material is formed and the colored plastic material is embedded therein and extended longitudinally of the direction of calendering, passing said intermediate sheet continuously in its longitudinal direction at calendering speed to a second bite in the calendering operation, and controlling the temperature at said second bite with respect to the calendering speed to produce a folding mottling bank at said second bite wherein the colored plastic material embedded in said intermediate sheet is extended laterally of the direction of calendering.

References Cited inthe file of this patent UNITED STATES PATENTS 

5. METHOD OF PRODUCING PLASTIC SHEET HAVING A MARBLED APPEARANCE, IN A CALENDER HAVING A BAFFLE BETWEEN THE TOP ROLL AND THE OFFSET ROLL, WHICH COMPRISES CONTINUOUSLY FEEDING HOT GRANULES OF BASE PLASTIC MATERIAL BETWEEN THE TOP ROLL AND THE BAFFLE. SIMULTANEOUSLY CONTINUOUSLY FEEDING COLD SLIVERS OF COLORED PLASTIC MATERIAL BETWEEN THE OFFSET ROLL AND THE BAFFLE IN SUBSTANTIALLY ALIGNED RELATION TRANSVERSE TO THE DIRECTION OF CALENDERING WHEREBY THE COLORED PLASTIC MATERIAL IS EMBEDDED IN THE BASE PLASTIC MATERIAL AND FORMED INTO A LONGITUDINALLY CONTINUOUS INTERMEDIATE SHEET, PASSING SAID INTERMEDIATE SHEET ON THE TOP ROLL CONTINUOUSLY IN ITS LONGITUDINAL DIRECTION AT CALENDERING SPEED TO A PARALLEL ROLL THEREBELOW, AND CONTROLLING THE TEMPERATURE ON SAID TOP ROLL WITH RESPECT TO THE CALENDERING SPEED TO FORM A BANK WHEREIN THE ONCOMING SHEET ON THE TOP ROLL ENCOUNTERS THE BANK AT THE BITE BETWEEN THE TOP ROLL AND THE ROLL THERERBELOW, DOUBLES OVER AND RETURNS TO SAID BITE IN MULTIPLE THICKNESSES OF SUPERIMPOSED FOLDS. 